Such technologies are used to assay one or more analytes with which the dry-chemical test element is loaded. To this end, a plurality of assay regions are formed on the test element, for example in the form of strips or other areas such as circles or squares, in which the one or more analytes accumulate following the application of a quantity of a liquid sample to be assayed (cf., for example, U.S. Pat. No. 6,707,554 B1). Usually, the analytes are labelled directly and are thus prepared for a subsequent optical analysis of the dry-chemical test element. The preparation of the dry-chemical test element may optionally also include rinsing or washing with a buffer solution, a diluting solution or a washing solution. Finally, the dry-chemical test element can then be analyzed by optical scanning, in order to ascertain in particular the occurrence of one or more specific analytes in the assay regions of the test element.
During the optical scanning, measurement light beams which are produced in the scanned assay regions are detected by a detector device after leaving the assay regions. The measurement light beams can be produced by applying test light beams, which for their part are produced by a suitable monochromatic or polychromatic light source, to the assay regions which are loaded with optically active substances to be measured. In the assay regions, the light of the test light beams then interacts with the optically active substances, resulting in a corresponding change in the optical properties of the test light beams, which then leave the assay region as measurement light beams. When test light is applied, the transmission, the reflection or the fluorescence may be assayed as optical properties of the measurement light beams. Measurement light beams may also be based on a luminescence of the optically active substances in the assay regions.
A measurement light intensity, with which the measurement light beams leave a respective assay region, may be different for the analyzed assay regions. By way of example, a fluorescent light produced in the respective assay region by means of the test light beams may be emitted with a different intensity, which may for example be an indicator of the concentration of an analyte to be measured. The intensity of transmitted measurement light depends inter alia on the extent of the optical absorption in the observed assay region. In the case of assaying by means of fluorescence, the extent thereof depends inter alia also on the concentration of the11 fluorescent molecules.
During the optical scanning of the dry-chemical test element, for example the test element and the detector device, by means of which the measurement light beams are detected, or the test element and the light source may be displaced relative to one another, in order thus to optically analyze assay region after assay region. According to the known procedure for optical scanning, certain scanning parameters are set before the start of the scanning process, with which a scan is then carried out. Usually a constant scanning speed and an exposure time for the detector device are set. If the measurement light beams are then emitted from the assay regions on the dry-chemical test element with a different intensity, the problem arises that in regions with a low measurement light intensity, which usually corresponds to a low concentration of the analyte to be measured, in some circumstances the scanning speed is too high to actually pick up a detected signal suitable for analysis. In other regions with a high analyte concentration, the light intensity of the measurement light beams leaving the assay region may in turn be so high that overloading of the detector device occurs at the preset scanning speed.